Muonium chemistry in liquids: Evidence for transient radicals

Abstract

Polarized positive muons are stopped in solutions in magnetic fields transverse to their polarization. Positrons from the asymmetric decay are detected as the muons precess, allowing measurement of the magnitude and direction (phase) of the apparent initial polarization $P_{\mathrm{res}}$. Variations of $P_{\mathrm{res}}$ with reagent concentration are compared with theoretical predictions. Measurement of both magnitude and phase of $P_{\mathrm{res}}$ allows sensitive tests of the mechanism of "fast" ${\mu }^{+}$ depolarization. Evidence is found for both epithermal "hot-atom" reactions and chemical reactions of muonium involving formation of rapidly reacting radicals. Chemical rate constants are extracted and compared with rates for analogous reactions of atomic hydrogen.